Stable cyclic (alkyl)(amino) carbenes as ligands for transition metal catalysts

A transition metal complex comprising a carbene ligand having the formula:

• wherein
• the A ring is a 4-, 5-, 6- or 7-membered ring;
• L is a linking group of from one to four ring vertices selected from the group consisting of C, O, N, B, Al, P, S and Si with available valences optionally occupied by H, oxo or Ra substituents;
• R is a member selected from the group consisting of C1-10 alkyl, C2-10 alkenyl, C2-10 alkynyl and aryl, wherein each is optionally substituted Ra substituents;
• R1 and R2 are members independently selected from the group consisting of C1-10 alkyl, C2-10 alkenyl, C2-10 alkynyl, aryl, C1-10 alkoxy, C2-10 alkenyloxy, C2-10 alkynyloxy, aryloxy, C2-10 alkoxycarbonyl, C1-10 alkylthio, C1-10 alkylsulfonyl and C1-10 alkylsulfinyl, or optionally are combined to form a 3- to 12-membered spirocyclic ring, said spirocyclic ring being optionally substituted with Rb substituents;
• wherein each Ra and Rb is independently selected from the group consisting of C1-10 alkyl, C2-10 alkenyl, C2-10 alkynyl, aryl, C1-10 alkoxy, C2-10 alkenyloxy, C2-10 alkynyloxy, aryloxy, C2-10 alkoxycarbonyl, C1-10 alkylthio, C1-10 alkylsulfonyl, C1-10 alkylsulfinyl, oxo, amino, imines, nitrogen heterocycles, hydroxy, thiol, thiono, phosphorus and carbene groups.